Fluorite (calcium fluoride) forms almost always in cubes, less commonly as octahedrons, and occasionally as globular masses. Its four perfect cleavage planes make cleaving of octahedrons possible. It is primarily used for the fluoridation of water for toothpaste. Fluorite crystals can glow under ultraviolet rays, hence the word fluorescence. It forms in a great variety of colors: blue, violet, yellow, green, and rarely pink. Recent discoveries in China of unusually large specimens have enabled artists to create a variety of carvings that emphasize the inherent beauty of the deep purple, blue, and green banding. Nicknamed “The Genius Stone,” it is associated with the advancement of the mind, concentration, and comprehension.